Global Sea Level Is Rising But How Bad Is It?
Global warming has been causing a lot of changes to the Earth and its environment. One of the most talked-about issues is the global sea level rise. Many of us may have vague knowledge of rising seas or melting ice sheets. But how bad is the global sea level rise?
According to NASA’s Global Mean Sea Level (GMSL) Integrated Multi-Mission Ocean Altimeter Data for Climate Research, the global mean sea level is rising at about 3.3 mm/year, since 1992 to present. Other data from NOAA Climate.gov show that the global mean sea level has risen about 21–24 cm or 8–9 inches since 1880. What is more, a third of this rise came in just the last two and a half decades. In other words, the global average sea level has been rising at a faster rate in recent decades.
The map in the visual content shows the sea level changes across the globe from 1993 to 2019, pulling the data from NASA. Although there are regional differences in sea level rise, some regions of the world ocean are rising at more than 6 mm/year.
Why Is Global Sea Level Rising?
There are primarily two factors that cause sea level rise. The two factors are related to global warming:
- added water from melting ice sheets and glaciers
- expansion of seawater due to rise of ocean temperatures.
As discussed earlier, some regions are more affected than others. This is because thermal expansion varies across the ocean. According to NASA‘ s explanation, currents and winds move the newly warmed and expansive water around, and that warmer water influences the strengths and patterns of ocean currents.
Meltwater from ice sheets and glaciers that cover Antarctica and Greenland causes about two-thirds of global sea level rise. Greenland is losing its ice at 277 gigatonnes per year, and Antarctica at 151 gigatonnes per year. Not sure how big is this amount of ice? One gigaton is enough to cover New York City’s Central Park in ice 305 meters or 1,000 feet deep! Then, the sea level rises by 1 mm for every 360 gigatonnes of ice lost. Rising sea levels at 3.3 mm/year means 1,188 gigatonnes of ice is melting away every year.
How Much Will Sea Level Rise in Near Future?
If all the ice sheets that cover Antarctica and Greenland and the mountain glaciers around the world were to melt, the global sea level would rise about 70 meters or 230 feet. Well, this is an unlikely scenario in near future as some scientist say it would take 5,000 years to melt all ice. But how about in coming decades?
A NOAA Climate.gov report predicts that global sea level will likely rise at least 0.3 meters or 12 inches above 2000 levels by 2100, even if the greenhouse gas emissions follow a lower pathway. What if the world didn’t follow a low greenhouse gas emission pathway? Then, the sea level could rise up to 2.5 meters or 8.2 feet above 2000 levels by the end of this century.
How Will Future Sea Level Rise Affect Us?
The global sea level is rising at an unprecedented rate. If this continued, what could happen? One of the latest estimates by Nature Communications shockingly suggests that 630 million people may live on land below projected annual flood levels for the end of the century. In other words, 630 million people could be forced to flee from their homes because of sea level rise by 2100.
11 Cities Could Disappear Due to Increased Coastal Flood
Still not getting your head around how serious it could be? That’s understandable; it is hard to grasp climate change unless it directly starts affecting you. To be fair, we cannot really imagine how ice sheet melting in Antarctica is connected to our daily life. However, the truth is rising sea level causes more coastal flooding and tidal flooding across the world. Risk of high tide flooding could increase especially in coastal communities or in an island nation. Therefore rising seas threaten infrastructure. In particular, World Economic Forum lists 11 coastal cities that could disappear by 2100 due to tidal flooding. These cities are:
- Jakarta, Indonesia
- Lagos, Nigeria
- Houston, Texas
- Dhaka, Bangladesh
- Venice, Italy
- Virginia Beach, Virginia
- Bangkok, Thailand
- New Orleans, Louisiana
- Rotterdam, The Netherlands
- Alexandria, Egypt.
These sea level rise projections could sometimes sound exaggerated or unlikely. However, it definitely helps us remind ourselves that global warming is not just about hotter temperature — it affects the whole environmental system as well as natural ecosystems of the Earth. And slowing global warming requires us humans to come together and take collective action for future generations.
Climate Change Is Real
In the Australian election 2022, climate change was the defining topic. It is never too late to learn about what is happening on the Earth and how the world is reacting to the issue. Here are some of the infographics related to the climate change on InsightsArtist: